This invention relates to a machine tool incorporating an operating unit which is movable by means of at least one first linear motor along a first guide structure in the direction of a first axis of travel and along a second guide structure in the direction of a second axis of travel by means of at least one second linear motor, jointly with said first guide structure. Each linear motor features a primary element and a secondary element.
A machine tool of this type, model TRUMATIC(copyright) HSL 2502 C, is currently being marketed by the Trumpf GmbH and Co., of 71254 Ditzingen, Germany. The functional or operating unit of that machine is in the form of a laser cutting head which, driven by linear motors, moves in a horizontal x-y plane. The first guide structure is a bridge that extends in the x-direction and guides the laser cutting head in the x-direction. A second guide structure is provided by the machine frame that carries the bridge with the laser cutting head on support beams and allows the bridge to travel in the y-direction. Linear motors, each with a primary element and a secondary element, serve to move the laser cutting head on the bridge and to move the laser cutting head and bridge assembly along the support beams of the machine frame. The secondary motor elements associated with the y-axis are attached to the support beams of the machine frame while their matching primary motor elements are attached to the bridge. Also connected to the bridge is the secondary element of the linear motor that drives the laser cutting head in the x-direction. The primary motor element operating in the x-direction is attached to the laser cutting head.
German Patent A-35 34 214 describes an x-y table encompassing as its operating unit a platform that is supported on a base by an intermediate carriage. Linear motors with primary and secondary elements move the platform on the intermediate carriage along the y-axis and the platform and carriage combination on the base in the x-direction. The primary motor elements controlling the movement along the different coordinates are attached to the top surface of the carriage facing the platform and, respectively, to the bottom surface of the carriage facing the base opposite the primary elements. Correspondingly, the primary motor elements for the different axes of travel of the platform are vertically separated by the body of the intermediate carriage. As a result, the overall height of that earlier design of an x-y table is rather considerable.
U.S. Pat. No. 6,130,490 discloses an x-y table in which the primary elements of the linear motors operating in different axes of travel are positioned in one common plane. That x-y table, however, does not encompass an intermediate structure comparable to the first guide structure in machine tools of the category here addressed. Moreover, in that prior art x-y table, the primary motor elements controlling the different axes of travel are positioned at a distance from one another along each axis of travel, resulting in an expansive overall design.
It is the objective of this invention to provide a corresponding machine tool with a compact configuration of a linear motor operated direct drive for at least one operating unit of the machine.
It has now been found that the foregoing and related objects may be readily attained in a machine tool with an operating unit that can be moved by a first linear motor along a first guide structure in the direction of a first axis of travel (z-axis) and by at least one second linear motor jointly with the first guide structure along a second guide structure in the direction of a second axis of travel (y-axis). Each linear motor includes a primary element and a secondary element. The secondary elements associated with the first axis of travel (z-axis) are operatively connected to the operating unit, and the secondary elements associated with the second axis of travel (y-axis) are operatively connected to the second guide structure. The primary elements associated with the different axes of travel (y-axis, z-axis) are operatively connected to the first guide structure and are positioned between the secondary elements associated with the first axis of travel (z-axis), The secondary elements associated with the second axis of travel (y-axis), and the primary elements (19/1, 19/2, 20) associated with the different axes of travel (y-axis, z-axis) are arranged in a linear side-by-side array in the direction of one axis of travel (y-axis) while mutually overlapping in the direction of the other axis of travel (z-axis).
The side-by-side arrangement makes it possible to position the primary elements associated with the different axes of travel in a direction perpendicular to the operating plane defined by the axes of travel of the operating unit, thus minimizing the system""s overall height. The overlapping of the primary elements along the respective axis of travel has a corresponding effect. As an added benefit of the compact design of the direct linear drive for the operating unit of machine tools per this invention, the mass that must be moved in the operation of the machine tool is minimized. That in turn allows for extraordinarily high travel speeds of the operating unit without compromising its positional accuracy. Machine tools built in accordance with this invention thus permit precise machining with extremely short processing cycles.
Preferably, the primary elements associated with the different axes of travel (y-axis, z-axis) overlap in full mutual superposition in the direction of the first axis of travel (z-axis). As a result, the space taken by the primary elements for the different axes of travel is minimized in the direction of the axis of travel in which they overlap.
Desirably, the primary elements associated with the different axes of travel (y-axis, z-axis) are arranged in a linear side-by-side array in the direction of the second axis of travel (y-axis) while mutually overlapping in the direction of the first axis of travel (z-axis).
The practicality of this configuration manifests itself by virtue in that, in the direction of the second axis of travel, it is the primary elements and, in the direction of the first axis of travel, it is at least one secondary element, i.e., at least one secondary element operatively connected to the operating unit, that are to be moved. The operating principle is that the movement of primary elements should always cover the longer travel paths while the movement of secondary elements should be limited to the shorter travel paths. The dimensions of the primary elements in the direction of the first axis of travel are particularly small, and this makes it possible to efficaciously guide the primary elements in the direction of the second axis of travel by means of a second guide structure that is also relatively small in the direction of the first axis of travel. It follows that the second guide structure extending in the direction of the second or xe2x80x9clongxe2x80x9d axis of travel can be slim in design.
The primary elements associated with the different axes of travel (y-axis, z-axis) mutually overlap in a direction perpendicular to the operating plane defined by the axes of travel (y-axis, z-axis) of the operating unit. The primary elements associated with the different axes of travel (y-axis, z-axis) are mutually offset in the direction perpendicular to the operating plane defined by the axes of travel (y-axis, z-axis) of the operating unit, while the primary elements associated with an axis of travel (y-axis, z-axis) opposite the other primary elements are so positioned as to face the matching secondary elements.
This geometric offset creates a relatively large distance between the primary elements controlling one of the axes of travel and the secondary elements associated with the respective other axis of travel. This eliminates possible interference, for instance by eddy currents, that might obstruct the movement of the operating unit or the joint movement of the operating unit and a first guide structure along the different axes of travel.
The joint movement of the operating unit and the first guide structure in the direction of the second axis of travel (y-axis) is provided by an even number of multiple linear motors. In the direction of the axis of travel concerned (y-axis), the primary elements of these linear motors are evenly distributed on both sides of the primary elements associated with the first axis of travel (z-axis).
Thus, the primary elements associated with the second axis of travel are driven in symmetry with the primary elements for the first axis of travel.
Each of the primary elements associated with the different axes of travel (y-axis, z-axis) is provided with a partial housing compartment. These housing compartments together form a modular primary element housing which is equipped with at least one common port shared by several primary elements and accommodating at least one external power supply cable, the leads of at least one external monitoring circuit and the leads of at least one external control circuit.
By positioning the primary elements associated with the different axes of travel in close mutual proximity, they can be jointly accommodated in a common primary element housing. The housing for the primary elements has at least one common input and/or output port from/to external lines and the number of external primary element input and output cables that travel along with the movement of the operating unit is reduced to a minimum. The housing compartments that make up the housing for the primary elements, like the primary elements themselves, may be mutually positioned for instance side by side or overlapping in one or several directions. Claim 8 describes practical ways in which common connections can be provided for the primary elements.
The primary element housing may also accommodate at least one coolant feed line, and the leads of at least one temperature monitoring circuit.